1. Field of the Invention
This invention relates to apparatus useful for releasably securing one or more devices, especially well tools, to the free end of a conduit such as coiled tubing or pipe prior to running the conduit into a well bore.
2. Description of Related Art
The use of coiled tubing for running tools or other devices into the bore of an oil or gas well is well known. Coiled tubing is made of steel and is typically delivered to a well site on truck-mounted spools or reels and run into a well bore inside production tubing or casing that is already in place. Coiled tubing is made in various nominal diameters ranging, for example, from ¾ to 4½ inches, with nominal diameters of 1¼ inches to 2½ inches being quite common. Because coiled tubing is most often made by roll forming and welding a continuous strip of steel, a raised seam line often extends longitudinally down the inside wall of the tubing. Except for the seam line, the inside and outside wall surfaces of coiled tubing are typically smooth.
The use of external or internal slip connectors for releasably attaching well tools to coiled tubing and pipe is also well known. However, the conventional, commercially available slip connectors typically fit only a single wall thickness of tubing or pipe. Even for coiled tubing having a specified nominal diameter, the wall thickness and actual inside diameter can vary significantly depending upon factors such as manufacturer, material, use cycles, temperature, loading and the like. In the past it has been necessary, for example, to purchase and inventory as many as nine different sizes of slip connectors for use with coiled tubing having a nominal diameter of 1¼ inches.
Slip connectors are therefore needed that can be used easily and effectively with coiled tubing and pipe having different wall thicknesses for a given nominal diameter.